The present invention relates to a veneer lathe for cutting off a veneer from a turned log, and more particularly to a veneer lathe provided with log driving means in the form of threaded cylinders.
In a series of inventions directed to rotating a log by exerting a force onto its periphery, a common element is a drive roller provided with a plurality of edged members on its periphery and disposed slightly ahead of the knife edge. (See, for example, U.S. Patent application Ser. No. 861,278; filed Dec. 16, 1977, entitled "Vereer Lathe" and invented by Katsuji Hasegawa assignor to the assignee of the present patent application).
The principle object of such series of inventions aims at exerting a force onto the log periphery to reduce the load on the log core portion since inferior quality logs must be used for producing veneer nowadays. In order to achieve said object, it is essential to exert a driving force onto the log periphery slightly ahead of the knife edge. Indeed, the drive roller type veneer lathe is thus constructed. However, it is still unsatisfactory for minimizing the core load, because edged members mounted on the drive roll come into piercing engagement with the log periphery somewhat ahead of the knife edge. Also, if the roller position is changed for minimizing the distance between the knife edge and the engagement point, it is inevitable that edged members interfere with the blade of the knife due to the endless structure of the drive roll surface, resulting in the breakage of the edged members. It is also proposed to reduce the roller size but in this way the number of penetrating edged members decreases with the result that the log is not given a sufficient driving force.